Exemplary embodiments described herein relate to an energy storage system and a management method thereof, and more particularly, to an energy storage system having a combination of a plurality of electrochemical energy storage apparatuses having different characteristics, and a management method thereof.
New energy generally refers to energy generated by converting existing fossil fuels. Renewable energy generally refers to energy generated by converting sunlight, water, rainfall, biological organisms. Some specific forms of new energy includes, but are not limited to, fuel cells, hydrogen energy, etc. Some specific forms of renewable energy includes, but are not limited to, solar photovoltaic energy, solar thermal energy, bio-energy, wind power energy, hydro energy, etc.
An energy storage system (ESS) is a system storing new and renewable energy or residual energy of a grid in a chargeable and dischargeable battery, and supplying power to a load when needed. For example, an ESS may be a new and renewable energy power generation system represented by solar photovoltaic energy power generator connected to a power storage system. Korean Patent Laid-Open Publication No. 10-2013-0138611 discloses an energy storage system linked with a new and renewable energy power generation system.
Generally, an ESS is connected to a new and renewable energy source, an existing power grid, and an energy storage apparatus, which stores power from the new and renewable energy source or the existing grid. The ESS supplies power to a load from any one of the new and renewable energy source, the grid, and the energy storage apparatus when the load requires power. In the case where the load instantaneously increases during operation of the system, the energy storage apparatus is mainly used to compensate for an output power when the output becomes insufficient by configuring a super capacitor together with a battery.
However, a typical super capacitor has low energy density while a large capacity super capacitor is very expensive. Further, while the super capacitor is suitable in situations requiring a large output within a few seconds, such as for an elevator, etc., it is not suitable as a long term energy storage system for peak cut and peak shaving of power of a building, a factory, or the like.